Draft gear having emergency release means

ABSTRACT

An emergency release mechanism for draft gear apparatus that permits the draft gear to be restored to a normal condition after an emergency release without causing damage to the unit or requiring replacement of parts therefor. The draft gear unit is provided with a plurality of toggle joints which act as solid links under normal buff loads, but which are collapsible under collision forces. Bias springs urge the toggle joints back to their normal alignment whenever the load thereon is removed by pull-apart forces between the adjacent cars.

United States Patent 1 Jeffrey [11] 3,750,896 [451 Aug. 7, 1973 1 1 DRAFT GEAR HAVING EMERGENCY RELEASE MEANS [75] inventor: William B. Jeffrey, lrwin, Pa.

[73] Assignee: Westinghouse Air Brake Company, Wilmerding, Pa.

[22] Filed: Apr. 17, 1972 [21] Appl. No.: 244,384

[52] U.S. Cl. 213/75 R, 213/12, 213/18 [51] Int. Cl. B6lg 9/04, B613 3/00 [58] Field of Search 213/12, 14, 18, 75 R,

[56] References Cited UNITED STATES PATENTS I Larsson 213/45 2,802,581

Larsson 213/45 I, 2526 5 20 I I7 7 I l9 12 m 3,515,288 6/1970 Frill et a1. 213/12 Primary Examiner-Drayton E Hoffman Attorney-Ralph W. Mclntire, Jr.

[57] ABSTRACT normal buff loads, but which are collapsible under collision forces. Bias springs urge the toggle joints back to their normal alignment whenever the load thereon is removed by pull-apart forces between the adjacent cars.

5 Claims, 1 Drawing Figure BACKGROUND OF THE INVENTION In order to prevent extensive damage to rapid transit railway cars, which could occur by telescoping of the cars in the event of a collision, the cars may be provided at the ends thereof with anti-climber plates which are intended to prevent the end of one car from climbing up over the end of the adjacent car and thereby prevent telescoping of the cars. Complementing the anticlimber plates are draft gears provided with collapsible cushioning units which adequately cushion both buff and draft forces under normal conditions. Under collision conditions, the draft gear cushion units are designed to collapse so that sufficient relative travel between adjacent draft gears is provided to permit engagement of the anti-climber plates. Once engaged the anti-climber plates limit the snap-back effect which the compressed cushioning units normally produce.

If draft gear apparatus is designed with shear or tension bolts or other such rupturable release mechanisms for providing the collapsiblefunction, it is obvious that following each incident of collapse, replacement of the broken release elements, such as the shear or tension bolts, is necessary to restore the draft gear to a working condition. In addition to unexpected collisions, it is also reasonable to expect that unusually severe couplings occur from time to time which are of sufficient severity to activate the collapsible units. The frequency with which collapse of the collapsible means of the draft gears may occur, makes it evident that a need exists for a simple yet effective release mechanism which can be simply restored to its normal operating condition without repair or replacement of parts.

SUMMARY OF THE INVENTION It is the object of the present invention therefore, to provide draft gear apparatus including cushioning means and collapsible release mechanism capable of withstanding normal buff forces but being collapsible, upon occurrence of a buff force exceeding a certain magnitude, to permit relative travel between adjacent draft gears to allow engagement of the anti-climber plates, said release mechanism being automatically restorable to its normal condition by simple application of pull-apart force to the draft gears and without repair or replacement of parts.

The object of the invention is attained by providing the draft gear apparatus with a plurality of toggle joints substantially axially disposed parallel to the line of forces acting on the cushioning unit, said toggle joints acting as solid links under normal buff loads for supporting the cushion element. Upon occurrence of colli sion forces, the cushion element is compressed sufficiently to cause action of a cam associated therewith to force the toggle joints radially outwardly over center, whereby the unit collapses to remove the cushion element support and allow unrestricted relative movement of the draft gear apparatus and consequently engagement of the anti-climber plates. When the buff forces are removed by pull-apart action on the draft gear apparatus, biasing springs urge the toggle joints to their normal disposition for restoring the apparatus to a normal active condition.

The single FIGURE drawing is an elevational view of an automatic coupler head and a draft gear apparatus,

mainly in section, by which said coupler head is mounted to a railway vehicle.

DESCRIPTION AND OPERATION As shown in the drawing, a draft gear unit 1 is horizontally pivotally supported in conventional manner at one end by a railway car under frame 2, of which only a portion is shown, with an automatic car coupler mat- .ing head 3 supported in conventional manner at the other end of said draft gear unit. The type of automatic car coupler, of which the mating head 3 is shown, is primarily used for rapid transit equipment, and for purposes of this invention, it will suffice to state that the coupler automatically performs the functions of coupling the cars, connecting air lines, and connecting electrical circuitry. Since the draft gear unit 1 and the mating head 3, as a unit, are horizontally pivotable within angular limits, centering means comprising a chain 4 and a spring 5 are connected to each other and between a bracket 6 fixed to the car and the mating head 3 for yieldably centering the mating head in a normal axially aligned position for engaging a counterpart mating head (not shown) on an adjacent car.

The draft gear unit 1 embodying the invention comprises a casing 7 in which a connecting rod 8 is coaxially slidably disposed, said connecting rod having a larger-diameter end 9 extending exteriorly of the casing and having a bracket 10 formed thereon for supporting the mating head 3. A guide member 11, in which the larger-diameter end 9 of connecting rod 8 is coaxially slidably supported, is secured to the end of easing 7 adjacent mating head 3. A smaller-diameter portion 12 of connecting rod 8 extends coaxially through casing 7, and the larger-diameter end 9 forms an annular shoulder 13 at the junction thereof with said smallerdiameter portion.

A sleeve-like cam member 14 coaxially surrounding the smaller-diameter portion 12 of connecting rod 8, is axially positionally adjustable thereon by being provided'with internal screw threads 15 at the end corresponding to the innermost end of said rod which is provided with complementary external screw threads 16.

When the cam member 14 is screwed into position on connecting rod 8, said cam member is screwed on sufficiently to cause a resilient annular cushion element 17 to be placed under a preselected'degree of compression between the shoulder 13 and a shoulder 18 formed by the free end of said cam member, said annular cushioning element being disposed in surrounding relation to the smaller-diameter portion 12 of the connectingrod. The end of cam member 14 and connecting rod 8 adjacent the screw threads 15 and 16 is loosely axially guided in an internal bore 19 formed in the rearward section of casing 7.

An annular slide member 20 is coaxiallyslidably disposed in surrounding relation on the end of cam member 14 adjacent cushion element 17. A plurality, such as three for example, of toggle joints 21 are equiangularly disposed in correspondingly spaced recesses 22 formed in the outerwall of easing 7 radially opposite the cam member 14. Each of the toggle joints 21 comprises a pair of arms 23 and 24 pivotally joined to each other at one end to form a knuckle at the mid-point of the toggle joint at which a rotatable circular cam follower 25 is carried. Each of the other ends of arms 23 are pivotally secured to the slide ring 20, and each of the other ends of arms 24 are pivotally secured to brackets 26 formed in the casing 7 at the corresponding opposite ends of the recesses 22 such that the toggle joints 21, when in normal extended positions, are disposed substantially parallel to the axis of the draft gear unit 1 coinciding to the axis of buff and draft forces applied to the draft gear unit.

Cam member 14 is provided, adjacent the end on which slide member is carried, with an annular cam surface 27 of the inclined plane type on which the circular cam followers of the toggle joints 21 are adapted to ride. A mouse trap type spring 28, or any other suitable spring means, may be used at each toggle joint 21 for biasing the toggle joint toward a normal radially retracted or axially extended position in which the cam follower 25 is in contact with the lowest point of cam surface 27.

In operation, when the coupler-draft gear assemblage is subjected to normal buff forces, the cushion element 17 is compressed between the shoulders 13 and 18 and yields sufficiently to absorb said normal buff forces. Such compression of the cushion element 17 may be sufficient to cause a limited amount of axial movement to the left, as viewed in the drawing, of the cam member 14 and connecting rod 8 relative to casing 7, so that the cam followers 25 begin to ride up on the inclined cam surface 27. Under such conditions of normal buff forces, however, the limited axial movement of cam member 14 and connecting rod 8 is not enough to cause cam surface 27 to be pushed under the cam followers 25 sufficiently to cause radial displacement of the toggle knuckles over dead center, but the toggle joints 21, that is, arms 23 and 24, are extended toward a substantially straight-line disposition and thus act as solid links exerting a support force on the cushion element 17 countering the buff forces.

Assuming, however, that buff forces of collision magnitude, that is, in excess of the maximum normal buff force at which the toggle joints 21 still remain in their normal positions, occur and are exerted on the draft gear unit 1. Under such collision conditions, the cushion element 17 is compressed sufficiently to produce enough axial displacement of cam member 14 to the left and, therefore, enough cam action between cam surface 27 and cam followers 25 to cause radial displacement of the toggle joint knuckles beyond dead center. With the displacement of the toggle joints 2] over dead center, that is, to a collapsed state, an emergency amount of axial movement of cam member 14 and, therefore, connecting rod 8 to the left relative to casing 7 occurs beyond the limited amount effected by normal buff forces, until the free end of said connecting rod abuts against a stop pad 29 formed internally of casing 7 at the end adjacent the underframe 2.

The emergency amount of axial movement of connecting rod 8 is sufficient to permit engagement of the anti-climber plates (not shown) mounted on the cross sills (not shown) of the respective cars, thereby preventing the end of one car from climbing up over the end of the other car and telescoping action of the two cars.

To reset the toggle joints 21 to their normal radially retracted positions, it is merely necessary to apply pullapart or draft forces to the draft gear unit 1, whereupon the connecting rod 8 and cam member 14 are restored to their normal positions relative to casing 7, and arms 23 and 24 of the toggle joints 2] are extended to a straight-line disposition in which the springs 28 are effective for restoring said toggle joints to their said normal radially retracted positions.

Having now described the invention, what we claim as new and desire to secure by Letters Patent, is:

1. Draft gear apparatus for use on railway vehicles and subjectable to buff and draft forces between adjacent vehicles, said draft gear comprising, in combination:

a. a substantially cylindrical casing mountable on one of the vehicles;

b. a connecting member disposed in said casing and axially movable relatively thereto when subjected to said buff and draft forces between the adjacent vehicles;

. cushioning means interposed between said casing and said connecting member to provide a resilient connection therebetween during draft and buffing action between the vehicles; and collapsible link means operably interconnected between said casing and said connecting member, said link means normally biased to an extended position in which axial movement of said connecting member relative to said casing, due to normal buff forces acting on said connecting member not exceeding a certain degree, is limited to a certain amount determined by the resulting compression of the cushioning means, and being operable, upon occurrence of buff forces acting on said connecting member in excess of said certain degree, to a collapsed position in which said axial movement of said connecting member relative to said casing may exceed said certain amount,

. said collapsible link means being restorable to its said extended position responsively to draft action between the two vehicles.

2. Draft gear apparatus, as set forth in claim 1, wherein said connecting member includes cam means effective, upon such axial movement of said connecting member in excess of said certain amount, for causing operation of said link means to its said collapsed position.

3. Draft gear apparatus, as set forth in claim 2, wherein said cam means comprises an axially disposed cam surface formed at one end of said connecting member, and said collapsible link means comprises an annular slide member and a plurality of toggle joints each having one end pivotally secured to said slide member and each having the opposite end pivotally secured to said casing at the end opposite said one end of said connecting member, each of said toggle joints being pivotally jointed at a midpoint between the ends thereof and carrying at said midpoint a cam follower, said toggle joints being normally biased toward a radially retracted position in which said cam follower is in contact with said cam surface, said cam surface and cam follower being cooperative upon axial movement of said connecting member in excess of said certain amount, for causing radial outward displacement of said toggle joints at their respective midpoints beyond dead center and consequent operation to the toggle joints to respective collapsed positions.

4. Draft gear apparatus, as set forth in claim 3, wherein said collapsible link means includes respective biasing means for biasing each of said toggle joints to said extended positions.

5. Draft gear apparatus, as set forth in claim 3, wherein said toggle joints are equi-angularly spaced in correspondingly spaced recesses formed in said casing radially opposite said cam surface on said connecting member and substantially parallel to the axis of said connecting member when in their respective retracted positions. 

1. Draft gear apparatus for use on railway vehicles and subjectable to buff and draft forces between adjacent vehicles, said draft gear comprising, in combination: a. a substantially cylindrical casing mountable on one of the vehicles; b. a connecting member disposed in said casing and axially movable relatively thereto when subjected to said buff and draft forces between the adjacent vehicles; c. cushioning means interposed between said casing and said connecting member to provide a resilient connection therebetween during draft and buffing action between the vehicles; and d. collapsible link means operably interconnected between said casing and said connecting member, said link means normally biased to an extended position in which axial movement of said connecting member relative to said casing, due to normal buff forces acting on said connecting member not exceeding a certain degree, is limited to a certain amount determined by the resulting compression of the cushioning means, and being operable, upon occurrence of buff forces acting on said connecting member in excess of said certain degree, to a collapsed position in which said axial movement of said connecting member relative to said casing may exceed said certain amount, e. said collapsible link means being restorable to its said extended position responsively to draft action between the two vehicles.
 2. Draft gear apparatus, as set forth in claim 1, wherein said connecting member includes cam means effective, upon such axial movement of said connecting member in excess of said certain amount, for causing operation of said link means to its said collapsed position.
 3. Draft gear apparatus, as set forth in claim 2, wherein said cam means comprises an axially disposed cam surface formed at one end of said connecting member, and said collapsible link means comprises an annular slide member and a plurality of toggle joints each having one end pivotally secured to said slide member and each having the opposite end pivotally secured to said casing at the end opposite said one end of said connecting member, each of said toggle joints being pivotally jointed at a midpoint between the ends thereof and carrying at said midpoint a cam follower, said toggle joints being normally biased toward a radially retracted position in which said cam follower is in contact with said cam surface, said cam surface and cam follower being cooperative upon axial movement of said connecting member in excess of said certain amount, for causing radial outward displacement of said toggle joints at their respective midpoints beyond dead center and consequent operation to the toggle joints to respective collapsed positions.
 4. Draft gear apparatus, as set forth in claim 3, wherein said collapsible link means includes respective biasing means for biasing each of said toggle joints to said extended positions.
 5. Draft gear apparatus, as set forth in claim 3, wherein said toggle joints are equi-angularly spaced in correspondingly spaced recesses formed in said casing radially opposite said cam surface on said connecting member and substantially parallel to the axis of said connecting member when in their respective retracted positions. 